Apparatus for cutting metals with liquid oxygen



Nov. 29, 1938.

G. M. DEMING 2,138,400

APPARATUS FOR CUTTING METALS WITH LIQUID OXYGEN Original Filed June 5, 1935 3 Sheets-Sheet 1 an (p .11 31,91. 10 o 4s 25 T am Z6 Z3 1.1:

T \L n INVENTOR ATTORNE Nov. 29, 1938. G. M. DEMING APPARATUS FOR CUTTING METALS WITH LIQUID OXYGEN Original Filed June 5, 1935 3 Sheets-Sheet 2 INVENTOR ATTORNEY Nov. 29, 1938. I v G. M. DEMING 2,138,400

APPARATUS FOR CUTTING METALS WITH LIQUID OXYGEN Original Filed June 5, 1.935 3 Sheets-Sheet 3 vi I I I ZO/NVENTOR g gflaxwzw,

' ATTORNEY Patented Nov. 29, 1938 UNITED STATES PATENT OFFICE APPARATUS FOR CUTTING METALS WITH LIQUID OXYGEN Original application June 5, 1935, Serial No.

25,009. Divided and this application October 16, 1936, Serial No. 105,873

8 Claims.

In the known practice of cutting metal with oxygen, a portion of the metal is usually brought to kindling temperature by one or more preheating flames and a jet of gaseous oxygen is directed against the heated spot. This jet, by rapid oxidation and some mechanical disintegration of the metal, makes an opening, which may be extended to form a kerf, or severance slot, by displacing the jet laterally to itself at a suitable rate of speed, or by moving the metal relatively to the cutting jet, which amounts to the same thing. This manner of cutting metal has great utility.

The object of this invention is greatly to increase the efliciency of oxygen cutting, and also to make it possible to cut through much larger thicknesses than it has been possible to out heretofore. The invention is based on the conception and discovery, contrary to what would be expected, that metal can be cut advantageously with oxygen in the liquid state. In carrying out the invention liquid oxygen only may be used for the cutting stream or streams, or separate cutting streams of gaseous oxygen and liquid oxygen may be used in conjunction.

This application is a division of application,

Serial No. 25,009, filed June 5, 1935, (Patent No. 2,094,641, dated October 5, 1937), for process for cutting metals with oxygen. The subject-matter of this application is the apparatus disclosed in the parent application for cutting with liquid oxygen. The features of novelty of this apparatus will become apparent from the detailed description of the preferred embodiments.

In the accompanying drawings forming part hereof: I

Fig. 1 is a view illustrating the cutting of: a thick piece of metal with one form of the apparatus, the apparatus being shown in side elevation and the Work in section;

Fig. 2 is a similar view illustrating cutting performed with another form of the apparatus,

Fig. 3 is a front elevation of the apparatus shown in Fig-1, a portion of the preheater torch being broken out; and

Fig. 4 is a vertical section taken through this apparatus, looking at right angles to Fig. 3.

Referring to Fig. 1, a supply of liquid oxygen is held in a heat-insulated reservoir 2. A stream 3 of the liquid oxygen is delivered through a cutting orifice in an outlet portion 4 connected with the lower part of the interior of the reservoir. This cutting orifice portion may be termed a nozzle, without implying any particular form which it may take. The stream 3 is shown attacking the body of metal 5 and cutting a kerf 6 therein. The direction of displacement of the apparatus and of the cutting stream to advance the cut is indicated by the arrow. If the apparatus remained stationary, the work would be moved in 5 the reverse direction, to the same effect. Associated with the cutting orifice there is a means 1 for applying one or more flame jets 8, to bring the metal to kindling temperature in thefflrst instance and to aid in the execution of the cut. This preheater has a burner tip 9, connections I0 and II to receive oxygen and combustible gas, and suitable mixing provisions (not shown).

In Fig. 2 a cutting torch I2 is disposed somewhat ahead of the liquid oxygen orifice, this torch constituting a means for delivering through an orifice H a cutting stream ii of gaseous oxygen. If an ordinary cutting torch is used it will include provisions for delivering one or more preheating flames I6; and the preheating means I need not be employed.

By using liquid oxygen and relying upon either the outer and gaseous envelope of the liquid stream or upon a separate gaseous oxygen stream to open the kerf. liquid oxygen, that is oxygen of high concentration and purity, may be delivered deep into the kerf. The cross-section of the liquid cutting stream is exceedingly small because the density of liquid oxygen is about eight bun-,- dred times that of gaseous oxygen. Because of its small cross-section, because of the much lower velocities of discharge that are appropriate for cutting with liquid oxygen, which velocities may be of the order often to twenty feet per second,

or more, and because a smoothly bounded liquid stream is more readily maintained than a gaseous stream, the pollution of the stream from the surrounding atmosphere, from preheating combustion gases and from the products of combustion of the metal is much less than in cutting with gaseous oxygen in the regular way. Since the time of delivery from the nozzle to the deeper portions of the cut is only a matter of a small fraction of a second, evaporation need not be so rapid that the liquid state will not persist at a considerable depth in the cut. This is particularly true if the process is carried out in the manner illustrated in Fig. 2 where the gaseous oxygen stream opens the upper portion of the out while the oxygen of the liquid stream is effective within the kerf and insures completion of the cut in the lower regions. In any case the use of a liquid oxygen stream for cutting makes .it possible to deliver purer oxygen into the cut and to have less pollution of the oxygen at any p given depth that would exist in cutting with gaseous oxygen as ordinarily, From this it follows that greater thicknesses of metal can be cut.

Apparatus for use in the process is shown in more detail in Figs. 3 and 4.

The reservoir 2 comprises an inner vessel holding the liquid oxygen, an outer shell 2|, heat insulating material 22 between these walls, a heat insulated cover 23, and a cam lever 24 for locking the cover tightly closed, this locking lever being fulcrumed on a shaft 25 carried by brackets 26 on a ring 21 secured to the outer shell 2|. Mounting brackets 28, which are shown broken away, serve to support the apparatus on a suitable feed mechanism (not shown) by which it can be moved in the desired direction of severance; or the apparatus may be supported in a stationary manner and the work be moved passage 3| 4 Means are provided for maintaining a con-' beneath it.

The liquid oxygen cutting nozzle 4 has. a stem 30 secured in an opening in the bottom of the inner vessel, this stem having a passage 3| which communicates at an angle with the delivery orifice 32. The cutting nozzle and the preheating tip 9 are surrounded by a jacket 33 containing heat-insulating material 34. The preheater torch may be supported on the outer shell of the liquid oxygen reservoir by a holder 35.

The walls of the cutting orifice 32 are parallel, and in this orifice, when the outlet is closed, there is a valve needle 36, the sides of which are straight and parallel. The valve needle is connected to or formed on a rod 31, which passes through a stufflng-box 38 in thetop of the nozzle 4 to the top of the reservoir, where it is pivoted to a valve lever 39 fulcrumed onthe shaft 25.

A limiting lug 40' on the fulcrum portion of the valve lever determines the extent of movement in opening and closing the cutting valve.

The relations are such that when the valve is closed it occupies the'delivery orifice 32, substantially filling it to the exit. In fact, as shown, the needle then projects somewhat beyond the outlet end of the orifice; and the end of the needle is cut of! square (not tapered) or' is otherwise formed so that in the act of closing it will shear oiT any excess rime that may have formed in the delivery orifice. When the orifice is closed any slight clearance between the valve needle and the walls of the orifice is quickly sealed by rime. The smooth surface of the needle results in the formation and preservation of a smooth lining for the cutting orifice. When the cutting valve is opened the needle 36 is withdrawn rearward or upward in the orifice 32 to .a position in which the extremity of the needle clears the junction bet een the orifice and the stant pressure inside the liquid oxygen reservoir, in order to discharge the liquid oxygen stream 3 at the requisite linear velocity. The pressure of the oxygen gas or vapor evolved from the liquid oxygen in the reservoir will itself serve as the operating pressure, and this pressure can be held to a definite value by a pressure relief valve 42, which may be adjustable or which may be replaced by other valves set for difl'erent pressures, if it is desired to vary the linear velocity of the liquid cutting stream.

To guard against excessive or hazardous pressure developing in the liquid oxygen reservoir, i not taken care of by the relief valve 42,, an emergency vent may be provided. To that end the cover locking lever 24 has a cam portion consisting of a heavy spring 48, which is rigid enough for all usual conditions but will yield when required to permit the cover to lift under excessiye internal pressure.

The apparatus shown in Fig. 2 is similar to that of Figs. 1, 3 and 4 except that the preheater torch 7 is not present and a gaseous oxygen cutting torch l2 is associated with the liquid oxygen cutting apparatus. This torch is shown mounted on the reservoir in a holder 50, which may be made adjustable.

I claim:

1. Apparatus for cutting metal comprising a thermally-insulated reservoir of liquid oxygen, a nozzle, and a parallel-sided needle valve in the nozzle, said valve having a sharp corner at its extremity for shearing rime from the walls of said nozzle..

2. Apparatus for cutting metal with liquid oxygen having a nozzle from which a cutting jet of liquid oxygen is delivered against the work, and a reciprocatory needle valve which, when closed, extends through said nozzle.

3. In apparatus for cutting metal with liquid oxygen, a portion having an orifice for delivering the liquid cutting jet, and a shut-off valve movable into said orifice at a location where said orifice is chilled and the valve is sealed by accumulation of rime.

4. Apparatus for cutting metal comprising a thermally-insulated reservoir of liquid oxygen, a nozzle which directs a stream of the liquid oxygen into a kerf in the metal to be cut, a valve controlling the supply of oxygen to the stream. and means for controlling. the velocity with which the oxygen stream is delivered into the kerf including an automatic pressure control device correlatedwith said nozzle and constructed and arranged to limit the gas pressure in the reservoir to a value that produces the desired velocity with said nozzle.

5. Apparatus for cutting metal comprising a thermally-insulated reservoir of liquid oxygen, a nozzle which directs a stream of the liquid oxygen into the metal to be cut, a valve controlling the steam, a relief valve to limit the pressure in the reservoir to a predetermined serves to shear rime from the walls of the nozzle.

'7. Metal cutting apparatus including a thermally-insulated reservoir for liquid oxygen, a nozzle from which said oxygen is directed as a liquid jet into the metal to be cut, a valve comprising a parallel-sided rod fitting the passage through the nozzle and movable into and out of said passage to cut off the jet of oxygen from the nozzle, means for moving the valve into a.

.closed position in which it extends through the passage to the discharge end of said passage, and a sharp corner at the termination of the parallel sides of the valve for shearing oif matter accumulated on the walls of the passage. v

8. Metal cutting apparatus including a reservoir for liquid oxygen comprising a vessel and 'a cover for said vessel, and thermal insulation over both the vessel and cover, a nozzle for directing a jet of liquid oxygen into the metal to be out,

means supporting the nozzle from said vessel, 7

a, passage through which liquid flows from the means being of such a nature that it yields in reservoir to the nozzle, a shut-off valve for conresponse to a. given pressure in excess of the trolling the supply of liquid to the nozzle, a. relief valve pressure so that the cover moves relief valve on the vessel limiting the pressure away from the vessel to increase the discharge at which the liquid is supplied to the nozzle, and of gas from the reservoir.

means locking the cover on said vessel, said GEORGE M. DEMIN 

